Such a rotary compressor is known from German Patent 2,261,336. In this case the lubricant, which is discharged from the compressor together with the compressed medium, is cooled by injecting a cooling medium. Due to the fact that this cooling medium evaporates in the space in which the mixture is compressed, the temperature of said mixture falls, which means that the oil temperature also falls.
This known method of cooling has the disadvantage that cooling medium in liquid form leaks through the gaps to be sealed with lubricant, as a result of which loss of output occurs. A second disadvantage is that the cooling medium disrupts the lubrication of the compression elements during the compression process, which reduces the operating reliability of the compressor.
In the absence of a device for cooling the lubricant in the compressor a heat exchanger is built into the system, taking up quite a large amount of space. This heat exchanger is then situated between the oil separating device and the lubricant injection point on the compressor.